Xcode Scroll View Auto Layout Issue when Embedding with Navigation Controller? - ios

I seem to be having issues when it comes to embedding a scrollview within a navigation controller. So here are the steps I take, and its really easy to replicate the weird error i seem to be getting.
1.) Drag and drop a UIViewController
2.) Followed by a UIScrollView
add constraints to UIScrollView, 0 on all sides, uncheck constrains to margins.
3.) Drag and drop another View into UIScrollView
add constraints to UIScrollView, 0 on all sides, uncheck constrains to margins.
Control drag from view into scroll view, make same width and height
After the following steps you will see in the following images that the view is not following the constraints I set, for some reason it thinks 0 is +64 from the top of scroll view? Not sure what I'm doing wrong here as it is very annoying visually.

In your view controller's attributes inspector, look for the Adjust Scroll View Insets and Extend Edges Under [Top|Bottom] Bar options.

Related

Autolayout with UIScrollView

I am using autolayout in Xcode and am creating a fairly tall (1300px) ViewController with a uiscrollview to navigate up and down. I made the viewcontroller freeform so its dimensions are [375,1300]. I then incorporated the scrollview, added the content view as well as all the subviews & constrained everything, leaving no constraint errors. At runtime there are no errors, but everything is all smushed into the normal screen size when I intended for it to be very tall (~1300px) and scrollable. Any clue as to what I am doing wrong?
Below is a diagram showing the issue where:
The Outer Black Blox is the ViewController's view
The Inner Black Boxes are subviews
and The Blue Box is what is displayed on the screen
Yes, your correct #Ryan Cocuzzo. I think you need to set sub view priority from 1000 to 250. See below screen shots.
1) Select height constraint of the subview
2)Then go to show to size inspector
3) Now change the priority constraint from 1000 to 250.
4)Finally you get like this
Make sure the following are true:
The 4 content views are subviews of the UIScrollView, not your view controller.
The autolayout constraints on the 4 content views must reference the UIScrollView only, not the view controller's view.
The 4th box cannot have a bottom constraint.
It looks like the 4th box has a constraint to make it's bottom align with the bottom of the view controller's view. This would force the other views to smush up together. The 4th box also cannot have a bottom constraint so that the scrollview can resize itself to encompass it's subviews.

Scroll views + Auto Layout in XIB: ambiguous scrollable content width

I have the following, simple layout: just a scroll view, with some views in it (please excuse the preview screenshot, since I'm using XIBs, there is no way to zoom out):
Here is my view hierarchy + constraints (the vertical constraints are all set up, throughout the view):
My problem with this case is that I get the following error in Interface Builder:
I've read up on the issue, I've found that I would need to add my scroll view as a subview to a simple view to silence this warning, but couldn't make it work (the view didn't scroll for some reason).
I think I understand the error here: the scroll view doesn't know, how far it can scroll horizontally, but I've found no way to specify this in IB (instead of setting it to a concrete value - which I don't want).
The problem is even more obvious, when I try to add another view to my hiearachy, and constrain its leading, trailing, and bottom edges to the scroll view:
The view just can't figure out its width, thus the messed up scrolling.
My question is the following: is there a good way to get rid of this ambiguity? In Storyboards, you can just add equal height/width constraints to the root view, but this is not an option with XIBs.
Okay, so I've managed to solve the issue with the following steps:
Use the following hierarchy: View of the xib ("main view") -> Additional view ("root view") -> Scroll view -> Additional view ("content view")
Pin the root view's edges to the main view so the screen is filled. Do the same for the scroll view (pin its edges to the root view's).
Define an "Equal Widths" constraint between the root view, and the content view. It's important to only constrain the width. My mistake was to also constraint the height, which caused the scroll view not to scroll.
Add any child views to the content view. Important note: you have to define the proper vertical constraints between the children, otherwise, the content view's height will be zero.
And that should be it! No more errors, and definitely no awkward scrolling glitches.

Gap between main view and scroll view using Auto Layout in navigation controller

I'm experiencing some trouble managing a scroll view embed inside a navigation view controller. I'm using Auto Layout and I'll try to explain the problem the best I can.
I embed a scroll view in the controller's main view and pinned the top, left, bottom and right borders to main view's borders.
I embed a standard UIView inside the scroll view and gave it a fixed height of 800 points. This should act as a container for all my controls (let's name it content view). Then again I pinned its top, left, bottom and right borders to the scroll view's borders. Because the bottom space constraint of scroll view's descendant view was negative, I adjusted it bringing it back to 0.
For the width, I CTRL-dragged from the content view to the main view and added a Equal widths constraint.
Finally, I added an image view and placed it at the top center of my content view adding some further trivial constraint.
The storyboard for the situation I've just depicted is shown above (in the document outline you should see all the constraints I've defined).
My scroll view works, it scrolls fine and the image view is well-centered where it's supposed to be. However, there's a gap between the end of the navigation bar and the start of the scroll view and I can't figure out why. It seems to be as high as the navigation bar, but I have no idea about how to fix it. The image shown below should make you understand what I'm talking about (the content view is highlighted in grey for clarity).
I didn't write a single line of code to achieve this result. I would really appreciate any kind of help and I'm ready to give you all the information you need to help me address the problem.
I think you should uncheck Adjust Scrollview Insets property of your viewcontroller to get rid of this....
you have to uncheck Adjust Scrollview Insets

Working with Top Layout Guide in UIScrollView through Auto Layout

I want to use the Top Layout Guide in the UIScrollView through Auto Layout. Without the UIScrollView Auto Layout works well with Top Layout Guide.
But when I embed the UIButton in UIScrollView, it doesn't.
I know that is because UIScrollView is not the same hierarchy level with Top Layout Guide. But I think there may be a good solution to resolve this issue.
You are right to be confused. It is a bit counterintuitive but the top and bottom layout guides are irrelevant to configuring a UIScrollView so that its scrollable content will underlap the translucent navigation bar, which is the effect you are trying to achieve.
what to do
Given the view hierarchy you've shown in the second picture, this is what you need to do on iOS8:
Configure the view controller so that "Extend Edges Under Top Bar" is checked (in code, use edgesForExtendedLayout). This will ensure that the view controller's lays out its root view so that it underlaps the nav bar.
Configure the scroll view constraints so that the scroll view's top edge has a zero offset from the top edge of its superview, not zero space from the top layout guide. This will ensure that the collection view fills the root view and thus also underlaps the nav bar, which is necessary for the scroll view's content to be able to scroll under the nav bar. (IB might fight you on this. See the footnote below.)
So now how do you make sure that the scroll view has any idea where the nav bar is, so that (for instance) it doesnt't always position its content under the nav bar? The answer has nothing to do with layout guides. In the view controller, check the box "Adjusts Scroll View Insets" (or in code, automaticallyAdjustsScrollViewInsets). This will cause the view controller to automatically adjust the scroll view's contentInset property so that the scroll view positions its content appropriately.
This will work.
what's going on
So why is this the answer? And why is it so confusing?
Frankly, it's easy to get confused because the top and bottom layout guides are prominently presented to us as elements that convey layout information about translucent overlaid elements. However, they are not the only "translucency-aware" layout mechanism. They are directly relevant only for positioning of "normal" subviews, i.e., not the view controller's root view, and not content within a UIScrollView.
Content within a scroll view (or a subclass like UICollectionView and UITableView) will always be positioned in a more complicated way involving the scroll the view itself, affected by properties like contentInset, contentOffset, etc.. (Really, if scroll view layout were a straightforward thing, why would Apple have dedicated WWDC sessions to scroll view layout for the last four years running?!)
To summarize, as the steps above indicate, the three distinct translucency-aware mechanisms for managing layout are as follows:
Extends Edges determines if the view controller positions its root view so that it underlaps the nav bar.
Layout Guides provide a metric that tells where the "main" content area is, taking translucent bars into account. You can use these with Auto Layout to position normal views so they don't underlap. Or you can access the numerical values in code.
Scroll View Insets are the right way to ensure that a scroll view's content can underlap but doesn't always underlap. The automaticallyAdjustsScrollViewInsets property on the view controller can do this for you automatically in simple cases. (Presumably, this property just causes the view controller to update the scroll view's contentInset based on the same values it exposes via the layout guides. So if you needed to manage the insets yourself, that's how you would do it.)
fighting IB's layout guide mania
A footnote on "Fighting with IB":
Unfortunately, Interface Builder might fight you when you try to constrain the scroll view edge to its superview's edge. If you do a ctrl-drag from the scroll view to the superview, when it pops up the menu of possible constraints to add between those views, it might try to get you to constrain the scroll view against the view controller's layout guides. This is because IB mindlessly prefers layout guides to superview edges, when the superview is the root view. But when you're working with a scrollview, this is the wrong thing.
Why? For instance, suppose you accept a constraint against the layout guide. Then you will end up with a top constraint on your scrollview that constrains it to topLayoutGuide-64.0. That -64.0 is a hard-coded value compensating for the exact height of a nav bar. So what happens when one fine day the nav bar does not equal 64pt? Or when you simply turn off the nav bar entirely? Or want to re-use this scene in a context without a nav bar? Answer: then you get a broken layout.
So how do you force IB to add a constraint from the scroll view to its superview's edge, as opposed to the layout guide? As far as I can tell, the answer is that you can't add that constraint correctly in IB by doing a ctrl-drag between views.
Instead, you need to select the view, and then use the "Pin" control at the bottom of the canvas. This is the one that looks like a capital H with a box in its middle. In the top section of the Pin popup dialog, the section with the little diagram showing superview space constraints, you can use the dropdown controls next to the text fields to configure if the space constraint binds a layout guide or a superview. This is shown below:
Github link to demo projects: https://github.com/algal/ScrollViewUnderlapDemo
While algal's answer seems to have worked prior to iOS 9.0 it is unnecessarily complicated and broken beyond iOS 9.0. The easier way that also works beyond iOS 9.0 and requires no interaction with auto layout is to simply do the following:
Ensure Adjust Scroll View Insets is checked for the ViewController in Interface Builder (or set automaticallyAdjustsScrollViewInsets to true programmatically).
Set the class of the ViewController's root View to UIScrollView in Interface Builder (or replace it (self.view) manually with an UIScrollView in code).
While adding spacing constraints, Xcode does not show items which have negative distance with your view. It seems you added a vertical space constraint between UIScrollView and UIView. Delete that constraint, move your scroll view to below Top Layout Guide and add a new vertical space constraint between UIScrollView and Top Layout Guide.

How to use UIScrollView in Storyboard

I have a scroll view with content that is 1000px tall and would like to be able to lay it out for easy design on the storyboard.
I know it can be done programmatically but I really want to be able to see it visually. Every time I put a scroll view on a view controller it won't scroll. Is it possible to get it to work like I want or do I have to do it in the code?
I'm answering my own question because I just spent 2 hours to find the solution and StackOverflow allows this QA style.
Start to finish here is how to make it work in storyboard.
1: go to you view controller and click on Attribute Inspector.
2: change Size to Freeform instead of Inferred.
3: Go to the main view on that storyboard, not your scrollview but rather the top level view.
4: Click Size Inspector and set this view to your desired size. I changed my height to 1000.
Now you will see that you storyboard has your view setup so you can see the entire height of your scroll for easy design.
5: Drop on a scrollview and stretch it so it takes up the whole view. You should now have a scrollview with size of 320,1000 sitting on a view in your view controller.
Now we need to make it scroll and need to make it show content correctly.
6: Click on your scrollview and click on Identity Inspector.
7: Add a User Defined runtime attribute with KeyPath of contentSize then type of SIZE and put in your content size. For me it is (320, 1000).
Since we want to see our whole scroll view on the storyboard we stretched it and it has a frame of 320,1000 but in order for this to work in our app we need to change the frame down to what the visible scrollview will be.
8: Add a runtime attribute with KeyPath frame with Type RECT and 0,0,320,416.
Now when we run our app we will have a visible scrollview has a frame of 0,0,320, 416 and can scroll down to 1000. We are able to layout our subviews and images and whatnot in Storyboard just the way we want them to appear. Then our runtime attributes make sure to display it properly. All of this without 1 line of code.
Here are the steps with Auto Layout that worked for me on XCode 8.2.1.
Select Size Inspector of View Controller, and change Simulated Size to Freeform with height 1000 instead of Fixed.
Rename the view of View Controller as RootView.
Drag a Scroll View as subview of RootView and rename it as ScrollView.
Add constraints for ScrollView:
ScrollView[Top, Bottom, Leading, Trailing] = RootView[Top, Bottom, Leading, Trailing]
Drag a Vertical Stack View as subview of ScrollView and rename it as ContentView.
Add constraints for ContentView:
ContentView.height = 1000
ContentView[Top, Bottom, Leading, Trailing, Width] = ScrollView[Top, Bottom, Leading, Trailing, Width]
Select Attributes Inspector of ContentView, and change Distribution to Fill Equally instead of Fill.
Drag a View as subview of ContentView and rename it as RedView.
Set Red as the background of RedView.
Drag a View as subview of ContentView and rename it as BlueView.
Set Blue as the background of BlueView.
Select RootView, and click Update Frames button.
Update Frames is a new button in Xcode8, instead of Resolve Auto Layout Issues button. It looks like a refresh button, located in the control bar below the Storyboard:
View hierarchy:
RootView
ScrollView
ContentView
RedView
BlueView
View Controller Scene (Height: 1000):
Run on iPhone7 (Height: 1334 / 2):
Here are the steps that worked for me on iOS 7 and XCode 5.
Drag a ViewController (it comes with UIView "View").
1.1 Select "View Controller" and select "File Inspector" and uncheck "Auto layout".
Drag a ScrollView (as child of ViewController's UIView "View")
Select ScrollView and open "Identity Inspector".
Enter "contentSize" for keyPath. Select "Size" for Type. And Enter {320, 1000} for value.
Note: Step 4 is simply saying that the scroller contains some content whose size is 320x1000 units. So setting contentSize will make scroller work.
Select View Controller, Select "Attributes Inspector" then select Freeform from Size.
Note: step 5 will allow us to change the size of "View" that the view controller comes with.
Select "View" and then select "Size Inspector".
Set Width to 320 and height to 1000.
Note: 5, 6 & 7 is purely for us to see stretched or entire expanded view inside StoryBoard.
Note: Make sure to unselect "Auto Layout" on View Controller.
Your View hierarchy should look like:
After hours of trial and error, I've found a very easy way to put contents into scrollviews that are 'offscreen'. Tested with XCode 5 & iOS 7. You can do this almost entirely in Storyboard, using 2 small tricks/workarounds :
Drag a viewcontroller onto your storyboard.
Drag a scrollView on this viewController, for the demo you can leave its size default,
covering the entire screen.
Now comes trick 1 : before adding any element to the scrollView, drag in a regular 'view' (This view will be made larger than the screen, and will contain all the sub elements like buttons, labels, ...let's call it the 'enclosing view').
Let this enclosing view's Y size in the size inspector to for example 800.
Drop in a label onto the enclosing view, somewhere at Y position 200, name it 'label 1'.
Trick 2 : make sure the enclosing view is selected (not the scrollView !), and set its Y position to for example -250, so you can add an item that is 'outside' the screen
Drop in a label, somewhere at the bottom of the screen, name it 'label 2'. This label is actually 'off screen'.
Reset the Y position of the enclosing view to 0, you'll no longer see label 2, as it was positioned off screen.
So far for the storyboard work, now you need to add a single line of code to the viewController's 'viewDidLoad' method to set the scrollViews contents so it contains the entire 'enclosing view'. I didn't find a way to do this in Storyboard:
- (void)viewDidLoad
{
[super viewDidLoad];
self.scrollView.contentSize = CGSizeMake(320, 800);
}
You can try doing this by adding a contentSize keyPath as a size to the scrollView in the Identity Inspector and setting it to (320, 1000).
I think Apple should make this easier in storyboard, in a TableViewController you can just scroll offscreen in Storyboard (just add 20 cells, and you'll see you can simply scroll), this should be possible with a ScrollViewController too.
Getting Scrolling to work in iOS7 and Auto-layout in iOS 7 and XCode 5.
In addition to this: https://stackoverflow.com/a/22489795/1553014
Apparently, all we need to do is:
Set all constraints to Scroll View (i.e. fix scroll view first)
Then set distance-from-scrollView constraint to the bottom most item to scroll view (which is the super view).
Note: Step 2 will tell storyboard where the last piece of content lies within Scroll view.
For this example, I have unchecked the Autolayout feature of the Interface builder. And, I'm still using (for no reason at all) the relatively old 4.6.1 version of Xcode.
Start with a view controller that has a scroll view over it (the main view).
1: Add a Container View, from the Object Library, to the scroll view. Notice that a new view controller is added to the storyboard and it is linked to the view controller with the scroll view.
2: Select the container view and, on the Size Inspector, make it anchor to top and left without auto resizing.
3: Change its height to 1000. (1000 is used for this example. You should apply the value that you require.)
4: Select the new view controller and, from the Attributes Inspector, change Size to Freeform.
5: Select the view of the new view controller and, on the size Inspector, change the height to 1000 (which is equal to the container view's height).
6: For your test later, while still on the view of the new view controller, add a label at the top and at the bottom of the view.
7: Select the scroll view from the original view controller. On the Identity inspector, add an attribute with the keyPath set to contentSize, type set to Size, and value set to {320, 1000} (or your container view's size).
8: Run on the 4-inch iPhone Simulator. You should be able to scroll from the top label up to the bottom label.
9: Run on the 3.5-inch iPhone Simulator. You should be able to scroll from the top label up to the bottom label.
Remember that Xcode 4.6.1 can only build for iOS6 and below. Using this approach and building for iOS6, I am still able to achieve the same results when the app is run on iOS7.
Note that within a UITableView, you can actually scroll the tableview by selecting a cell or an element in it and scrolling up or down with your trackpad.
For a UIScrollView, I like Alex's suggestion, but I would recommend temporarily changing the view controller to freeform, increasing the root view's height, building your UI (steps 1-5), and then changing it back to the standard inferred size when you are done so that you don't have to hard code content sizes in as runtime attributes. If you do that you are opening yourself up to a lot of maintenance issues trying to support both 3.5" and 4" devices, as well as the possibility of increased screen resolutions in the future.
Disclaimer :- Only for ios 9 and above (Stack View).
If you are deploying your app on ios 9 devices use a stack view.
Here are the steps :-
Add a scroll view with constraints - pin to left, right, bottom, top (without margins) to superview (view)
Add a stack view with same constraints to scroll view.
Stack View Other Constraints :- stackView.bottom = view.bottom and stackView.width = scrollView.width
Start adding your views. The scroll view will decide to scroll based on the size of the stack view (which is essentially your content view)
Here's how to setup a scrollview using Xcode 11
1 - Add scrollview and set top,bottom,leading and trailing constraints
2 - Add a Content View to the scrollview, drag a connection to the Content Layout Guide and select Leading, Top, Bottom and Trailing. Make sure to set its' values to 0 or the constants you want.
3 - Drag from the Content View to the Frame Layout Guide and select Equal Widths
4 - Set a height constraint constant to the Content View
i wanna put my 5 cents to accepted answer:
i've been researching topic for 2 days and finally found a solution that i will be using always from now on
go up to item 4 in accepted answer and forget about adding attributes of frames and contentsizes and so on
to make everything automatic just use solution from this link
everything is clear, easy, elegant and works like a charm on ios 7. i'm pretty glad with all that lol
You should only set the contentSize property on the viewDidAppear, like this sample:
- (void)viewDidAppear:(BOOL)animated{
[super viewDidAppear:animated];
self.scrollView.contentSize=CGSizeMake(306,400.0);
}
It solve the autolayout problems, and works fine on iOS7.
Here is a simple solution.
Set the size attribute of your view controller in the storyboard to "Freeform" and set the size you want. Make sure it's big enough to fit the full content of your scroll view.
Add your scroll view and set the constraints as you normally would. i.e. if you wants the scroll view to be the size of your view, then attach your top, bottom, leading, trailing margins to the superview as you normally would.
Now just make sure there are constraints in the subviews of the scrollview that connect the top and bottom of the scroll view. Same for left and right if you have horizontal scrolling.
In iOS7 I found that if I had a View inside a UIScrollView on a FreeForm-sized ViewController it would not scroll in the app, no matter what I did. I played around and found the following seemed to work, which uses no FreeForms:
Insert a UIScrollView inside the main View of a ViewController
Set the Autolayout constraints on the ScrollView as appropriate. For me I used 0 to Top
Layout guide and 0 to Bottom layout Guide
Inside the ScrollView, place a Container View. Set its height to whatever you want (e.g. 1000)
Add a Height constraint (1000) to the Container so it doesn't resize. The bottom will be past the end of the form.
Add the line [self.scrollView setContentSize:CGSizeMake(320, 1000)]; to the ViewController that contains the scrollView (which you've hooked up as a IBOutlet)
The ViewController (automatically added) that is associated with the Container will have the desired height (1000) in Interface Builder and will also scroll properly in the original view controller. You can now use the container's ViewController to layout your controls.
Here's a bit of a grubby answer that get's to the same solution for vertical scroll views, but (against the ethos of stackoverflow) doesn't answer the question. Instead of using a scrollView, just use a UITableView, drag a normal UIView into the header, and make it as big as you want, you can now scroll the content in storyboard.
Apparently you don't need to specify height at all! Which is great if it changes for some reason (you resize components or change font sizes).
I just followed this tutorial and everything worked: http://natashatherobot.com/ios-autolayout-scrollview/
(Side note: There is no need to implement viewDidLayoutSubviews unless you want to center the view, so the list of steps is even shorter).
Hope that helps!
The key is the contentSize.
This is often missing and not indicated when adding a UIScrollView.
Select the UIScrollView and select the Identity Inspector.
Add a contentSize keyPath as a size to the scrollView in the Identity Inspector and setting it to (320, 1000).
Scroll away.
If you are using auto-layout than best approach is to use UITableViewController with static cells in storyboard.
I have also once faced the problem with a view that require much more scrolling so change the UIScrollView with above mentioned technique.

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